[Rd] Wrong move of NEWS item

[Martin Maechler]

>>>>> Suharto Anggono Suharto Anggono 
>>>>>     on Wed, 4 Mar 2026 06:05:18 +0000 (UTC) writes:

    > Then, please announce the change in NEWS. For example:
    > The result of arithmetic and comparison operations of non-overlapping "ts" objects where either is a matrix is now a matrix.

    > It seems that the statement "diff(<ts-matrix>) remains matrix, even when it has length zero" was meant for the change to 'Ops.ts'. But the wording is about diff(<ts-matrix>), which is included in the previous statement.

    > But I've just realized this.

    > Suppose that
    > x <- ts(0)

    > With the change, x - lag(x, -1) and x == lag(x, -1) are NULL.
    > In R 4.5.2, x - lag(x, -1) is integer(0) and x == lag(x, -1) is logical(0).

Indeed, so we may even have to change R-devel further (for this
rare boundary case).

But the R 4.5.2   x - lag(x, -1)  giving integer(0)  is only somewhat better than
giving NULL  when in principle the "truly correct" answer should
be  double(0) and we'd rather get that right in R-devel.

Re NEWS, you are right: I will add a small note, indeed {as it
is not "code" that's frozen}.


Martin



    > ________
    > On Tuesday, 3 March 2026 at 04:02:14 pm GMT+7, Martin Maechler <maechler using stat.math.ethz.ch> wrote:


>>>>> Peter Dalgaard
    >>>>>>     on Mon, 2 Mar 2026 14:37:22 +0100 writes:

    >     > I do hope Martin sees this. Code freeze for 4.5.3 is
    >     > Wednesday @0:02 ...  - Peter


    > Yes, I did see and think about it, but decided that it was "too
    > late" now, *and* not a "problem" I think:
    > `-` now exhibits the correct behaviour  but the diff()
    >     methods do not yet (but do in R-devel etc).

    > Martin

    >     >> On 28 Feb 2026, at 12.57, Suharto Anggono Suharto Anggono
    >     >> via R-devel <r-devel using r-project.org> wrote:
    >     >>
    >     >> Now that the NEWS item is gone from "CHANGES IN R 4.5.2
    >     >> patched", please also revert the change to 'Ops.ts' in
    >     >> R-4-5-branch, as I have mentioned. In R-4-5-branch, the
    >     >> change makes diff(m) inconsistent with m - lag(m, -1) for
    >     >> 1-row ts matrix m. Previously, neither of them was a
    >     >> matrix.
    >     >>
    >     >> _______ On Monday, 23 February 2026 at 07:16:36 pm GMT+7,
    >     >> Martin Maechler <maechler using stat.math.ethz.ch> wrote:
    >     >>
    >     >>
    >     >>>>>>> Suharto Anggono Suharto Anggono via R-devel on Sun,
    >     >>>>>>> 22 Feb 2026 03:58:13 +0000 (UTC) writes:
    >     >>
    >     >> > diff(m, lag, dif) for matrix m now still returns >
    >     >> matrices, also when lag * dif > nrow(m) (PR#18972, thanks
    >     >> to > Mikael Jagan and Suharto Anggono).  >
    >     >> diff(<ts-matrix>) remains matrix, even when it has length
    >     >> zero.
    >     >>
    >     >> > The above NEWS item has been moved to "CHANGES IN R
    >     >> 4.5.2 patched".
    >     >>
    >     >> > In fact, in R-4-5-branch, diff(m, lag, dif) for matrix
    >     >> m is still not a matrix when lag * dif > nrow(m) (see
    >     >> https://svn.r-project.org/R/branches/R-4-5-branch/src/library/base/R/diff.R
    >     >> for 'diff.default';
    >     >> https://svn.r-project.org/R/branches/R-4-5-branch/src/library/base/R/datetime.R
    >     >> for 'diff.POSIXt';
    >     >> https://svn.r-project.org/R/branches/R-4-5-branch/src/library/base/R/dates.R
    >     >> for 'diff.Date';
    >     >> https://svn.r-project.org/R/branches/R-4-5-branch/src/library/stats/R/ts.R
    >     >> for 'diff.ts').
    >     >>
    >     >> > And I suggest keeping it so. Because it has been like
    >     >> that simce the beginning, I think changing it in a patch
    >     >> release is not appropriate.
    >     >>
    >     >> We have ported bug fixes of "forever bugs" to the "R
    >     >> patched branch", before, quite on purpose.  Typically
    >     >> they have been really rare use cases and for that reason
    >     >> probably were not detected and reported earlier... and we
    >     >> (R core) still thought these bugs should disappear as
    >     >> quickly as possible.
    >     >>
    >     >> For the above reason(s), I *had* actually planned to port
    >     >> this bug fix also to R "4.5.2 patched" ...  But then it
    >     >> has become somewhat late to do the port only now, and R
    >     >> 4.5.3 will only be a "wrap up" release anyway..
    >     >>
    >     >> Hence, I agree with your opinion and will now move the
    >     >> NEWS entry instead of porting the bug fix which was the
    >     >> original plan.
    >     >>
    >     >> Martin
    >     >>
    >     >>
    >     >> > What have been ported to R-4-5-branch are just-
    >     >> replacing 'tsLag' with 'lag' in 'diff.ts'- 'Ops.ts' to
    >     >> return matrix when e1 or e2 is matrix but e1 and e2 are
    >     >> not overlapping > I suggest reverting the port. A
    >     >> justification of diff(m) for 1-row ts matrix m not being
    >     >> a matrix was that m - lag(m, -1) was not a matrix.  >
    >     >> Replacing 'tsLag' with 'lag' in 'diff.ts' is actually OK,
    >     >> but not necessary.
    >     >>
    >     >> [[alternative HTML version deleted]]
    >     >>
    >     >> ______________________________________________
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    >     >> https://stat.ethz.ch/mailman/listinfo/r-devel


    >     > --
    >     > Peter Dalgaard, Professor, Center for Statistics,
    >     > Copenhagen Business School Solbjerg Plads 3, 2000
    >     > Frederiksberg, Denmark Phone: (+45)38153501 Office: A 4.23
    >     > Email: pd.mes using cbs.dk Priv: PDalgd using gmail.com  
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